The apparatus for the projection exposure of the batch exposure system such as the step-and-repeat system or the scan exposure system such as the step-and-scan system have been used to transfer the pattern of the reticle (or photo-mask etc.) as the mask on the wafers (or vitreous plate etc.) as the substrates intended for exposure in the lithography process for fabricating semiconductor elements (or liquid crystal displays etc.). In the kind of apparatus for the projection exposure, it is desirable to transfer various kinds of pattern on the wafers with each high resolution.
The transferred pattern that requires very fine high resolution is the so-called contact hole. The contact hole includes the densely massed contact hole having a plurality of predetermined shaped aperture arranged with predetermined fine pitch and the isolated contact hole being substantially comprised of a single aperture. In order to transfer the pattern of the former densely massed contact hole on the wafer with high resolution, the so-called deformed illumination system (deformed light source system), which allows the amount of light of the illumination light to be enlarged in one or more areas (particularly four areas) being eccentric for optical axis at the pupil plane of the illumination system, is effective (refer to Japanese Patent Applications Laid-open No. Hei 5-67558 (corresponding with U.S. Pat. No. 6,094,305) and NO. 2001-176766 (corresponding to U.S. Pat. No. 6,563,567)).
On the other hand, in order to transfer the pattern of the later isolated contact hole on the wafer with high resolution, the illumination system, which allows the amount of light of the illumination light to be enlarged in a relatively small round area centering optical axis at the pupil plane of the illumination system, that is, the illumination system that allows the σ value, being a coherence factor of the illumination system to be relatively lessened (hereinafter, it will be called “small a illumination system” for convenience of description), is known to be effective.